This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application entitled AN APPARATUS FOR PROCESSING IMAGE DATA earlier filed in the Korean Industrial Property Office on Jun. 23, 1998, and there duly assigned Serial No. 98-23683.
1. Field of the Invention
The present invention relates to an image data processing apparatus, and more particularly, to an image data processing apparatus in which an image having a continuous tone can be reproduced by a two-valued dot recorder.
2. Description of the Related Art
A dithering method using a two-valued dot recorder is for expressing a continuous tone, where the continuous tone is to number the degree of the shading, e.g., black is zero and white is 256 for the case in which 256 numbers are used to express the degree of the shading from white to black. According to the dithering method, ON or OFF of the dot is determined by a threshold value varied by the position of a pixel. At this time, the threshold value which is a matrix having the size determined by the number of a tone to be expressed, is determined by the position of the coordinate of an input pixel. For instance, the tone of 65 (0, 1, 2, . . . , 64) steps can be expressed in an 8xc3x978 matrix, and the tone of 145 steps can be expressed in a 12xc3x9712 matrix.
To solve the above problems, it is an objective of the present invention to provide an image data processing apparatus capable of easily predetermining the period and the angle of an optimum macroscopic dot in accordance with types of received image data or a user""s intention.
Accordingly, to achieve the above objective and other objectives of the present invention, an image data processing apparatus according to the present invention includes:
an input element determination unit for determining whether an input element provided by a computer is either a command for processing continuous tone data or continuous tone data;
a parameter input unit for receiving a parameter for processing the continuous tone data, when the input element provided by the computer is a continuous tone data processing command;
a parameter replacement unit for replacing the parameter received by the parameter input unit to an approximate value realized by a multiple-valued recorder;
a threshold-valued matrix selection unit for selecting a continuous tone screen threshold matrix on the basis of the parameter replaced by the parameter replacement unit;
a continuous tone data input unit for receiving the continuous tone data, and for transmitting the received continuous tone data, when the input element provided by the computer is the continuous tone data;
a continuous tone processing unit for converting continuous tone data transmitted through the continuous tone data input unit to multiple-valued data in accordance with a threshold-valued matrix selected by the threshold-valued matrix selection unit; and
an output unit for outputting data processed by the continuous tone processing unit to the multiple-valued recorder.
Here, preferably, the parameter comprises at least one of the period, the angle and the form of a macroscopic dot, the period is more early replaced than the angle when the parameter is replaced with an approximate value, and the multiple-valued recorder has a recording ability of steps 2 through 16, for example.
According to the present invention, the received parameter is replaced with the period of the macroscopic dot to be realized by the multiple-valued recorder, the size of the corresponding macroscopic dot is determined, and the threshold-valued matrix for processing a continuous tone is selected according to the angle and the form of the macroscopic dot, and then the image data having the continuous tone is converted to multiple-valued data in accordance with the threshold-valued matrix, to thereby easily predetermine the period and the angle of an optimum macroscopic dot in accordance with types of the received image data or a user""s intention.